Journal of Equine Veterinary Science 31 (2011) 722-731 Journal of Equine Veterinary Science journal homepage: www.j-evs.com Original Research Midline Cysts of Colliculus Seminalis Causing Ejaculatory Problems in Stallions Malgorzata A. Pozor DVM, PhD, Dipl ACT a, Margo L. Macpherson DVM, MS, Dipl ACT a, Mats H. Troedsson DVM, PhD, Dipl ACT, ECAR c, Claudia Klein DVM, PhD, Dipl ACT, ECAR c, Mohamadou Diaw DVM a, Claus Buergelt DVM, PhD, Dipl ACVP b, Liane Dillon a a Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL b Department of Infectious Diseases and Pathobiology, University of Florida, Gainesville, FL c Department of Veterinary Science, University of Kentucky, Lexington, KY article info abstract Article history: Cystic structures are often seen during ultrasound examination of the internal genitalia Received 4 March 2011 of stallions. They are located between the ampullae of deferent ducts, either within the Received in revised form urogenital fold, or under the isthmus of the prostate (uterus masculinus). Occasionally, 03 May 2011 cystic dilatations are also found more caudally, behind the prostate, at the colliculus Accepted 8 June 2011 seminalis (urethral cyst, utriculus masculinus). These cysts are detected less frequently Available online 27 July 2011 during routine examinations, possibly because of the fact that this area is screened less carefully for the pathologies than the more proximal portion of the internal reproductive Keywords: Midline cyst tract of stallions. We have recently noticed that many stallions with ejaculatory problems Utriculus have large cysts at the colliculus seminalis. This article describes the typical clinical Uterus masculinus presentation of these cases, diagnostic procedures, and management. In addition, we Ejaculatory dysfunction discuss the discrepancies in the currently used terminology pertinent to this condition, Stallion as well as introducing a new term, which seems to best describe the root cause of this disorder. Finally, this article presents new diagnostic and therapeutic options used in human medicine in similar cases, and proposes to investigate the applications of these methods in veterinary medicine. Ó 2011 Elsevier Inc. All rights reserved. 1. Introduction dysfunctions that are associated with partial or complete occlusion of the ampullae [3] . Ejaculatory dysfunctions in stallions occur rarely but Uterus masculinus, which is a cystic remnant of the are frustrating for horse breeders [1] . Various musculo- Müllerian ducts, has been occasionally associated with skeletal and neurologic diseases are responsible for ejaculatory problems in stallions [4]. However, this struc- the majority of these disorders, whereas only a small ture is also identi fied in stallions with normal ejaculatory percentage of them is associated with the ejaculatory patterns [5,6]. It is most often located between the terminal apparatus itself [1,2] . Diagnosis of speci fic causes of parts of the ampullae of deferent ducts, within the urogen- these dysfunctions is dif ficult and often unrewarding. ital fold, on the dorsal side of the bladder; or on the level of Dilatation of the terminal portion of the ampullae of the neck of the urinary bladder, underneath the prostatic deferent ducts, visualized during transrectal ultrasound isthmus (Fig.1A). A small lumen is often present in the mid- evaluation (TRUS), is often reported in cases of ejaculatory portion of this structure, which can be identi fied in many stallions during a routine ultrasound evaluation. Secretions Corresponding author at: Malgorzata A. Pozor, DVM, PhD, Dipl ACT, of the glandular epithelium may become trapped within this University of Florida, College of Veterinary Medicine, PO Box 100136, Gainesville, FL. lumen and may form cysts of various sizes and shapes E-mail address: pozorm@ufl.edu (M.A. Pozor). (Fig. 1B). Anterior part of the uterus masculinus often gives 0737-0806/$ - see front matter Ó 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.jevs.2011.06.004 M.A. Pozor et al. / Journal of Equine Veterinary Science 31 (2011) 722-731 723 Fig. 1. Internal genitalia in stallion (ub ¼ urinary bladder, a ¼ ampulla of deferent duct, v ¼ vesicular gland, p ¼ lobe of prostate, bu ¼ bulbourethral gland, u ¼ urethra, m ¼ uterus masculinus, c ¼ colliculus seminalis, um ¼ opening to utriculus masculinus, * ¼ cyst). (A) Dorsal view. ( B) Various locations of cysts. (C) Ventral view with the urethra cut open. off two cornua with blind ends. The posterior end, called a separate clinical entity, which deserves recognition by utriculus masculinus, continues its course beyond the practicing veterinarians. prostate, and opens into the urethra on the summit of the colliculus seminalis (Fig. 1C). Lack of this opening may lead 2. Presentation to the formation of a cyst at the colliculus seminalis, called prostatic utricle, cystic enlargement of utriculus masculinus, Typically, stallions with ejaculatory problems, associ- or urethral cyst ( Fig. 2A) [4,7]. Large cysts at this location ated with the midline cysts of the colliculus seminalis, may interfere with emission and the ejaculatory process in present to the clinic with a complaint of inconsistent some stallions (Fig. 2B) [6] Significant compression of the reproductive performance. They have periods with normal ejaculatory ducts (EDs) leads to a build-up of fluids in the sexual behavior and good semen quality, alternating with ampullae of deferent ducts and in the excretory ducts of the days or weeks of ejaculatory problems and/or poor semen vesicular glands. Small cellular concrements or large solid quality. Treatment with oxytocin and transrectal massage plugs form in the very terminal parts of deferent ducts as of the accessory sex glands only occasionally helps in a consequence of a long-term spermiostasis ( Fig. 2C). Gel obtaining an ejaculate, but these procedures are not secreted by the vesicular glands becomes very thick, dif ficult effective on many occasions. Frequent semen collections do to expel, and may completely plug the EDs. not prevent an occurrence of this disorder. There are also We have recently examined 10 stallions with cysts at cases, which present with a consistent history of long-term the colliculus seminalis, which contributed to the long- ejaculatory problems or infertility. term problems with the ejaculatory process ( Table 1 ). These cysts were located between the caudal edge of the 3. Evaluation prostate and the cranial pole of the bulbourethral glands, at the level of the colliculus seminalis. The affected stallions Evaluation of stallions with ejaculatory disorders showed a similar pattern of copulatory behavior, and follows the outline of the breeding soundness evaluation similar physical features in their internal reproductive recommended by the Society of Theriogenologists [8]. tract. Therefore, in this article, we describe this disorder as However, some modi fications are usually made. Fig. 2. Pelvic urethra (cross-section) at the level of colliculus seminalis in a stallion (u ¼ urethra, c ¼ colliculus seminalis, v ¼ excretory duct of the vesicular gland, d ¼ terminal part of deferent duct, e ¼ ejaculatory duct, * ¼ utriculus masculinus). (A) Diagram with normal utriculus masculinus communicating with a urethra. (B) Diagram with enlarged utriculus masculinus not communicating with a urethra (cyst of colliculus seminalis). ( C) Diagram with a cyst of colliculus seminalis, dilated excretory ducts of vesicular glands with thick plugs, and terminal parts of deferent ducts with solid concrements. 724 M.A. Pozor et al. / Journal of Equine Veterinary Science 31 (2011) 722-731 Table 1 Clinical examples of stallions with the midline cysts of the colliculus seminalis Case Age Breed Presenting Sexual Behavior Semen Shape Largest Dimension Number Year Complaint Characteristics of a Cyst of a Cyst (cm) 1 13 TB BSE Ejaculatory difficulties Normal Oval 1.13 2 17 QH Ejaculatory Ejaculatory difficulties Asthenozoospermia; Oval Spindle 1.0 difficulties bacterial plugs shape 4.0 3 10 QH Occasional Occasional ejaculatory Occasional Tear shape 1.5 Asthenozoospermia difficulties Asthenozoospermia 4 5 Paso Fino Short longevity of Strong stimulation Short longevity of Oval 1.5 sperm motility necessary sperm motility 5 13 Tennessee Azoospermia, Ejaculatory difficulties; Azoospermia, large Oval 1.5 Walking tailless heads discomfort percentage of tailless Horse heads of spermatozoa 6 8 Miniature Ejaculatory Ejaculatory difficulties High concentration Oval 0.54 Horse difficulties of spermatozoa; bacterial plugs 7 7 TB BSE Ejaculatory difficulties Normal Oval 1.13 8 4 Paint Anejaculation Ejaculatory difficulties Normal Oval and 1.2; 0.9; 0.5 rectangular (multiple) 9 8 Irish Draft Infertility Anejaculation Azoospermia Tear shape 1.2 10 4 Paso Fino Asthenozoospermia Low libido; strong Oligospermia; Oval 1.5 stimulation necessary Necrospermia 3.1. Sexual Behavior associated with the midline cyst of the colliculus seminalis retain strong sexual drive despite their symptoms. Stallions After conducting a complete physical examination of with occluded ampullae thrust multiple times, and often the affected stallion, evaluation of sexual behavior is always show behaviors accompanying ejaculation, such as tail performed. This can be done either in presence of an movements (flagging), or urethral contractions, but only ovariectomized mare showing strong estrous behavior, or seminal plasma is expelled under low pressure. They in a mare in natural